bacterial upper respiratory tract infections

Question 1

strep pyogenes

Answer 1

gram + cocci, chains
catalase - (no bubbling)
beta hemolytic
bacitracin sensitive, PYR +

Question 2

staphylococci

Answer 2

catalase + (bubbling)

tells apart from strep pyogenes

Question 3

how strep presents

Answer 3

pharyngitis, pyoderma, impetigo, erysipelas, cellulitis, necrotizing fasciitis, strep toxic shock

Question 4

30% of sore throats in kids is caused by

Answer 4

group A strep - pharyngitis

Question 5

signs of strep pharyngitis

Answer 5

petechiae in soft palate
inflammation in oropharynx

symptoms can inlude: nausea, vomiting, abdominal pan

Question 6

strep pyogenes and rheumatic heart disease

Answer 6

M protein, antiphagocytic on outer surface of group A strep –> triggers anti-cardiac Ab responsible for leaflet thickening and deposits and RHD
MOLECULAR MIMICRY

Question 7

haemophilus influenzae

Answer 7

gram - coccobacilli
curved ends on round rods
requires X AND V growth factors (both present in chocolate agar)
oxidase +

Question 8

what are the growth requirements of haemophilus influenzae

Answer 8

requires X AND V growth factors (both present in chocolate agar)
x is hemin/heat stable; V is Nad or nadp/heat labile
grows best in 5-10% co2

Question 9

types of h influenzae

Answer 9

6 capsular types a-f
type b are responsible for human diseases (primarily children)
nonencapsulated are normal flora in URT

Question 10

which type of h influenzae causes disease in humans?

Answer 10

type b capsular

polyribose-ribitol phosphate (PRP or Hib) capsule is antiphagocytic

Question 11

what protects from type b h influenzae?

Answer 11

antibody against PRP (polyribose ribitol phosphate) capsule

Question 12

type b h infuenzae diseases

Answer 12

mostly affects nonvaccinated children
meningitis
epiglottitis
pneumonia

Question 13

nonencapsulated h influenzae infections

Answer 13

acute atitis media and sinusitis——second to s pneumoniae
exaccerbations of COPD
conjunctivitis (daycare centers)
bacteremia/invasive infections in adults with underlying conditions

Question 14

type b h influenzae usually infects who in the developed world?

Answer 14

nonvaccinated young children or elderly

Question 15

how do anti-capsular antibodies protect humans?

Answer 15

they act as opsonins and mediate complement-dependent phagocytosis of the bacteria
Ab + complement can lead to bacterial lysis

Question 16

how to treat h influenzae infections?

Answer 16

cephalosporin or ampicillin

Hib vaccinations for kids

Question 17

what causes diptheria?

Answer 17

corynebacterium diphtheriae

Question 18

cornuebacterium jeikeium causes

Answer 18

infections in immunosuppressed and is frequently resistant to many antibiotics

Question 19

signs of diphtheria

Answer 19

incubation period 2-5 days
involves mucus membranes
classified by site (anterior nasal, tonsillar, laryngeal, ocular, genital, etc…)

Question 20

how diphtheria progresses

Answer 20

enters URT
colonizes mucosa
makes diphtheria toxin –> toxin gene inhibits protein synthesis
can cause myocarditis, neuritis, or necrosis
creates pseudomembrane after necrosis and then death by obstruction

Question 21

treatment for diphtheria

Answer 21

antitoxin - horse origin
antibiotic - kills bacteria BUT does not prevent intoxication
immunize with toxoid

Question 22

what bacteria has M protein virulence factor

Answer 22

group a streptococci pyogenes

Question 23

gram + rods that form chinese letters, non motile, non spore forming
catalase +

Answer 23

c diphtheriae

Question 24

how does c diphtheriae toxin work?

Answer 24

A-B single chain toxin that ADP-ribosylates EF-2 and stops protein synthesis
cytotoxic to cells

Question 25

prp conjugate vaccine is to prevent what bacteria

Answer 25

haemophilus influenzae